1. Field of the Invention
This invention relates generally to the field of perpendicular magnetic recording (or write) heads and more particularly, to a main pole and trailing shield thereof being made of bilayer trailing shield gap Rhodium (Rh) serving as a chemical mechanical planarization (CMP) stop layer and shield gap, part 1, and an Aluminum Oxide (Al2O3) layer serving as shield gap, part 2, and hard mask for controlling the pole width and beveling thereof to increase performance.
2. Description of the Prior Art
As the recording density of magnetic hard drives (or disk drives) increases, a physical limitation is experienced using longitudinal recording systems partly due to thermal relaxation known as super-paramagnetism. That is, the density requirements for meeting today's storage needs are simply not attainable with longitudinal recording systems. To provide further insight into this problem, it is anticipated that longitudinal recording systems will lose popularity as storage capacities in excess of about 150 Gigabytes-per-square-inches become a requirement. These and other factors have lead to the development and expected launch of perpendicular recording heads or write heads. Perpendicular recording is promising in pushing the recording density beyond the limit of longitudinal recording.
Accordingly, perpendicular recording potentially can support much higher linear density than longitudinal recording due to lower demagnetizing fields in recorded bits.
A magnetic recording head for perpendicular writing generally includes two portions, a writer for writing or programming magnetically-encoded information on a magnetic media or disk and a reader portion for reading or retrieving the stored information from the media.
The writer of the magnetic recording head for perpendicular recording typically includes a main pole and a return pole which are magnetically separated from each other at an air bearing surface (ABS) of the writer by a nonmagnetic gap layer, and which are magnetically connected to each other at a back gap closure (yoke). This structure is referred to as a single-pole write head because while a main pole and return pole are referred thereto, the return pole is not physically a pole, rather, it serves to close the loop with the main pole and the soft under layer of the media to form a magnetic flux circuit.
Positioned at least partially between the main and return poles are one or more layers of conductive coils encapsulated by insulation layers. The ABS is the surface of the magnetic head immediately adjacent to the recording medium.
To write data to the magnetic medium, an electrical current is caused to flow through the conductive coil, thereby inducing a magnetic field through the write head yoke, fringing across the write head gap at the media. By reversing the polarity of the current through the coil, the polarity of the data written to the magnetic media is also reversed.
The main and return poles are generally made of a soft magnetic material. The main pole generates magnetic field in the media during recording when the write current is applied to the coil.
In perpendicular recording heads, writing and erasing of information is performed by a single-pole write head. The main pole is composed of high moment magnetic materials, the most common example being cobalt-iron (CoFe) alloys or laminate layers.
With the advent of perpendicular recording heads, density has been greatly increased, as discussed hereinabove, which has lead to a greater need for accurate recording of data onto the desired track. That is, writing to adjacent tracks is highly undesirable because it causes corruption of data on adjacent tracks.
Perpendicular write heads generally have a trailing shield, side shields, a main pole and a bottom return pole. The main pole is generally shaped in a manner causing a tip or an extension thereof that is narrower than the remaining portion thereof to form a top pole. The side shields act to shield the main pole so as to reduce adverse affects on adjacent tracks during the writing of magnetic transitions (data) at a location on a given track. One of the problems associated with prior art perpendicular write heads is controlling the critical gap thickness, i.e. the thickness between the main pole and the trailing shield. Another problem associated with prior art perpendicular write heads is controlling main pole width and bevel angle. But perhaps the more severe problem therewith remains main pole damages and corner rounding caused from chemical mechanical planarization (CMP) process, such as described in further detail below.
In the perpendicular recording head with trailing shield, the main pole and trailing shield are separated by the gap layer, thus, requiring improvement for controlling the formation of the gap layer so as to have well-controlled critical gap thickness between the main pole and the trailing shield.
The main pole is generally beveled (or trapezoidal) in shape in an effort to reduce adjacent track writing. Controlling the pole width so as to better line up with the track to be written thereto needs further improvement, as does controlling the angle of the bevel of the bevel-shaped design of the main pole.
It is vital for the corners of the bevel of the main pole to be straight rather than rounded, which is often experienced during manufacturing of the main pole and trailing shield. Such corner rounding generally results in the magnetic field that is induced onto the disc to be curved rather than straight. This effect adversely impacts system performance by degrading accurate recording of data onto the disc, as well as, unnecessarily higher power consumption.
Thus, in light of the foregoing, there is a need for a perpendicular recording head having a main pole and trailing shield manufactured to pattern the main pole and to eliminate main pole corner rounding while having well-controlled critical gap thickness between the main pole and the trailing shield.